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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A triangulation based approach to three dimensional geoscientific modelling

Lattuada, Roberto January 1999 (has links)
No description available.
12

3-D-Oberflächenerfassung- und 3-D-Druck-Potentiale für gerichtsverwertbare kriminaltechnische Untersuchungen

Schubert, Rainer, Mittasch, Marcus 10 December 2016 (has links) (PDF)
Was führt kriminaltechnische Sachverständige zur Konferenz Entwerfen Entwickeln Erleben Es mag ungewöhnlich sein, dass sich hier Kriminaltechniker bzw. kriminaltechnische Sachverständige zu Wort melden. Bedenkt man, dass sich die Kriminaltechnik ja nahezu ausschließlich naturwissenschaftlicher Methoden bedient, so sind allein hierin schon Berührungspunkte vorgegeben. Für uns ist es die Erprobung einer neuen Methode, sich ganz konkret an den Lehrstuhl Konstruktionstechnik/CAD zu wenden. Wir glauben im Übrigen nicht, dass es ungewöhnlich ist, dass die Kriminaltechnik mit universitären Einrichtungen zusammenarbeitet. Immerhin, wenn man in ihre Geschichte schaut, hat sich die Kriminaltechnik aus Zweigen einzelner Naturwissenschaften entwickelt.
13

Relief representation : time to get 'back to basics'?

McCrorie, Ian January 1995 (has links)
This thesis examines the evolution of the now dominant contour method of relief representation, associated interpretation problems and attempted solutions. A hybrid method of relief representation is then suggested combining a standard topographic map, to provide quantitative data, and computer generated three-dimensional visualisations, to give topographic structure. The hypothesis that this system will result in improved performance at relief interpretation tasks, particularly for inexperienced map users, was then tested. A second aspect of the hypothesis centred on the colouring of the 3-D views. Thus the experiment was expanded to assess if the more natural impression provided by layer colouring resulted in improved performance. The principle evaluation involved 2 Objective Tests of user performance. Subjective assessment of 3-D visualisation production and quality and Opinion Samples were also used in the overall evaluation. This thesis concludes that the three-dimensional information tested here has not produced the expected improvement. Reasons suggested for this include lack of training with 2 and 3 dimensional data, unfamiliarity with computer generated three-dimensional views and inability of inexperienced map users to manipulate complex three-dimensional imagery. Suggested improvements to the theory include increased training and use of more specifically targeted views, for example, to illustrate a walking route using a series of views along its course.
14

Commissioning of a 3-D manual missing tissue compensator cutter

Nakatudde, Rebecca 10 September 2009 (has links)
Background: Many cancer patients who require external beam radiotherapy such as breast cancer patients, present with irregular surface topographies and tissue inhomogenieties in the treatment field. Such irregularities give rise to unacceptable dose non-uniformity. Standard fields cannot be applied without compensation for missing tissue. 1-D and 2-D missing tissue compensators can be used but they have limitations. 3-D compensators are the most effective but they are normally fabricated using very expensive automated systems. Objectives: To study the variation of linear attenuation coefficients of different materials in megavoltage photon beams, select a tissue equivalent compensating material and commission a local 3-D manual missing tissue compensator cutter. Methods and materials: Linear attenuation coefficients were measured for tin, River sand mix, Lincolnshire bolus and dental modelling wax for different energy megavoltage photon beams. Measurements were done in a water phantom using a cylindrical ionisation chamber at varying depths. The CT numbers and densities of the materials were also measured. Negative plaster of paris moulds of the breast and head and neck areas were made using a RANDOTM Alderson anthropomorphic phantom from typically simulated fields. 3-D missing tissue compensators were then fabricated on the manual cutter and were tested for their effectiveness during treatment delivery. Results: Linear attenuation coefficients were dependent on photon beam energy, the thickness and density of the attenuator, but independent of the depth of measurement for compensator thickness of more than 2 cm. Lincolnshire bolus and dental modelling wax with CT numbers of –78 ± 9 and -88 ± 18 and densities of 1.4 ± 0.0 g/cm3 and 0.9 ± 0.0 g/cm3 respectively can be regarded as tissue equivalent materials. The fabricated 3-D missing tissue compensators were effective in correcting for dose non-uniformities compared to fields with no beam-modifying devices or wedges (1-D compensators). Conclusions: The 3-D missing tissue compensators were effective in correcting for dose non-uniformities in treatment fields involving very irregular surface topographies compared to 1-D and 2-D methods. They can be fabricated cheaply using a 3-D manual missing tissue compensator cutter. Quality control procedures need to be followed during fabrication.
15

Massively Parallel Implementations of Theories for Apparent Motion

Grzywacz, Norberto, Yuille, Alan 01 June 1987 (has links)
We investigate two ways of solving the correspondence problem for motion using the assumptions of minimal mapping and rigidity. Massively parallel analog networks are designed to implement these theories. Their effectiveness is demonstrated with mathematical proofs and computer simulations. We discuss relevant psychophysical experiments.
16

Techniques to minimize circuitry and improve efficiency for defect tolerance

Rab, Muhammad Tauseef 05 November 2013 (has links)
As technology continues to scale to smaller geometries and newer dimensions (3-D), with increasingly complex manufacturing processes, the ability to reliably manufacture 100% defect-free circuitry becomes a significant challenge. While implementing additional circuitry to improve yield is economically justifiable, this thesis addresses the cost of defect tolerance by providing lower cost solutions or alternatively more defect tolerance for the same cost in state-of-the-art ICs, including three-dimensional ICs (3-D ICs). Conventional defect tolerance techniques involve incorporating redundancy into the design. This thesis introduces novel designs to maximize the utility of spare elements with minimal circuitry overhead, thereby improving the yield. One idea proposed is Selective Row Partitioning (SRP), a technique which allows a single spare column to be used to repair multiple defective cells in multiple columns. This is done by selectively decoding the row address bits when generating the select signals for the column multiplexers. This logically segments the spare column allowing it to replace different columns in different partitions of the row address space. All the chips are identical, but fuses are used to customize the row decoding circuitry on a chip-by-chip basis. An implementation procedure and results are presented which show improvement in overall yield at a minimal overhead cost. Moreover, new yield-enhancing design techniques for 3-D ICs are introduced. When assembling a 3-D IC, there are several degrees of freedom including which die are stacked together, in what order, and with what rotational symmetry. This thesis describes strategies for exploiting these degrees of freedom to reduce the cost and complexity of implementing defect tolerance. One strategy is to enable asymmetric repair capability within a 3-D memory stack by exploiting the degree of freedom that the order of the die in the stack can be selected. This technique optimizes the number of fuses, and in some cases, the number of spares as well, required to implement defect tolerance. Another innovative technique is to exploit rotational symmetry of the dies to do implicit reconfiguration to implement defect tolerance. Results show that leakage power and performance overhead for defect tolerance can be significantly reduced by this technique. / text
17

A four-wing chaotic attractor generated from a new 3-D quadratic autonomous system

QI, G, Chen, G, van Wyk, MA, van Wyk, BJ, Zhang, Y 02 January 2007 (has links)
This paper introduces a new 3-D quadratic autonomous system, which can generate two coexisting single-wing chaotic attractors and a pair of diagonal double-wing chaotic attractors. More importantly, the system can generate a fourwing chaotic attractor with very complicated topological structures over a large range of parameters. Some basic dynamical behaviors and the compound structure of the new 3-D system are investigated. Detailed bifurcation analysis illustrates the evolution processes of the system among two coexisting sinks, two coexisting periodic orbits, two coexisting single-wing chaotic attractors, major and minor diagonal double-wing chaotic attractors, and a four-wing chaotic attractor. Poincare´-map analysis shows that the system has extremely rich dynamics. The physical existence of the fourwing chaotic attractor is verified by an electronic circuit. Finally, spectral analysis shows that the system has an extremely broad frequency bandwidth, which is very desirable for engineering applications such as secure communications.
18

The use of induced stereoscopic motion for photographic interpretation

Slingerland, Douglas Alan, 1930- January 1967 (has links)
No description available.
19

Magnetotelluric imaging of Precambrian lithosphere beneath southern Alberta

Nieuwenhuis, Greg Unknown Date
No description available.
20

Three dimensional vision by laser triangulation

Henry, G. K. January 1988 (has links)
No description available.

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